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1.
A. U. Mallik 《Environmental management》1995,19(5):675-684
Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into
heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil
acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed
habitats.
If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged
unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest
vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation
shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation. 相似文献
2.
Pickett ST Cadenasso ML Grove JM Boone CG Groffman PM Irwin E Kaushal SS Marshall V McGrath BP Nilon CH Pouyat RV Szlavecz K Troy A Warren P 《Journal of environmental management》2011,92(3):331-362
Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs. 相似文献
3.
Justin D. Burdine 《Local Environment》2018,23(2):198-219
Urban gardens are important sources of sustenance for communities with limited access to food. Hence, this study focuses on food production in gardens in the Toledo metropolitan area in Northwest Ohio. We administered surveys to 150 garden managers from November 2014 to February 2015 in our attempt to better understand how neighbourhood racial composition and poverty levels are related to staffing and voluntarism, food production and distribution, the development of infrastructure, and the adoption of sustainability practices in urban gardens. The results from 30 gardens are presented in this paper. We used Geographic Information Systems to map the gardens and overlay the map with 2010 census data so that we could conduct demographic analyses of the neighbourhoods in which the gardens were located. Though the gardens were small – two acres or less – up to 46 varieties of food were grown in a single garden. Gardens also operated on small budgets. Food from the gardens was gifted or shared with friends, family, and neighbourhood residents. Gardens in predominantly minority neighbourhoods tended to have fewer institutional partners, less garden infrastructure, and had adopted fewer sustainable practices than gardens in predominantly White neighbourhoods. Nonetheless, residents of predominantly minority and high-poverty neighbourhoods participated in garden activities and influenced garden operations. Volunteering and staffing were racialised and gendered. 相似文献
4.
Using Paleo Reconstructions to Improve Streamflow Forecast Lead Time in the Western United States 总被引:2,自引:0,他引:2
Christopher Carrier Ajay Kalra Sajjad Ahmad 《Journal of the American Water Resources Association》2013,49(6):1351-1366
In water stressed regions, water managers are exploring new horizons that would help in long‐range streamflow forecasts. Oceanic‐atmospheric oscillations have been shown to influence streamflow variability. In this study, long‐lead time streamflow forecasts are made using a multiclass kernel‐based data‐driven support vector machine (SVM) model. The extended streamflow records based on tree ring reconstructions were used to provide a longer time series data. Reconstructed data were used from 1658 to 1952 and the instrumental record was used from 1953 to 2007. Reconstructions for oceanic‐atmospheric oscillations included the El Niño‐Southern Oscillation, Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and North Atlantic Oscillation. Streamflow forecasts using all four oscillations were made with one‐year to five‐year lead times for 21 gages in the western United States. This is the first study that uses both instrumental and reconstructed data of oscillations in SVM model to improve streamflow forecast lead time. SVM model was able to provide “satisfactory” to “very good” forecasts with one‐ to five‐year lead time for the selected gages. The use of all the oscillation indices helped in achieving better predictability compared to using individual oscillations. The SVM modeling results are better when compared with multiple linear regression model forecasts. The findings are statistical in nature and are expected to be useful for long‐term water resources planning and management. 相似文献
5.
Collisions with deer and other large animals are increasing, and the resulting economic costs and risks to public safety have made mitigation measures a priority for both city and wildlife managers. We created landscape models to describe and predict deer-vehicle collision (DVCs) within the City of Edmonton, Alberta. Models based on roadside characteristics revealed that DVCs occurred frequently where roadside vegetation was both denser and more diverse, and that DVCs were more likely to occur when the groomed width of roadside right-of-ways was smaller. No DVCs occurred where the width of the vegetation-free or manicured roadside buffer was greater than 40 m. Landscape-based models showed that DVCs were more likely in more heterogeneous landscapes where road densities were lower and speed limits were higher, and where non-forested vegetation such as farmland was in closer proximity to larger tracts of forest. These models can help wildlife and transportation managers to identify locations of high collision frequency for mitigation. Modifying certain landscape and roadside habitats can be an effective way to reduce deer-vehicle collisions. 相似文献
6.
Donald L. Chery Calvin G. Clyde Roger E. Smith 《Journal of the American Water Resources Association》1979,15(4):1126-1145
ABSTRACT: Mathematical models for predicting watershed surface flow responses are available, most of which are elaborate nonlinear numerical surface and channel flow models linked with infiltration models. Such models may be used to make predictions for ungaged areas, assuming an acceptable fitting of the model to the topography and roughness of the real system. For some application purposes, these models are impractical because of their complexity and expensive computer solutions. A procedure is developed that uses a complex model of an ungaged area to derive a simpler parametric nonlinear system model for repetitious simulation with input sequences. The predicted flow outputs are obtained with the simpler model at significant savings of money and time. The procedures for constructing a complex kinematic model of a 40 acre (161,880 m2) reference watershed and deriving the simpler system model are outlined. The results of predictions from both models are compared with a selected set of measured events, all having essentially the same initial conditions. Peak discharges ranged from 3 to 118 ft3/sec (0.085 to 3.34 m3/sec), which includes the largest event of record. The inherent limitations of lumped systems models are demonstrated, including the bias caused by their inability to model infiltration losses after rainfall ceases. Computer costs and times for the models were compared. The derived simple model has a cost advantage when repeated use of a model is required. Such an applications hydrologic model has an engineering tradeoff of reduced accuracy, and lumping bias, but is more economical for certain design purposes. 相似文献
7.
Calvin P. C. Poon Frank J. DeLuise 《Journal of the American Water Resources Association》1967,3(4):26-35
Manganese entering impounded water will undergo a cyclic transformation. Oxidation precipitates manganese from top waters. At the bottom of the lake, biological activity will render manganese soluble by both intracellular as well as extracellular activity. The study was made to demonstrate that biological reduction and transformation, organometallic complexation, together with the presence of carbon dioxide and the lowering of pH all have some effect on the solubility of manganese. Dissolved manganese may be brought back to top waters during the lake overturn and therefore deteriorates the water quality. 相似文献
8.
Water treatment residuals (WTR) can reduce runoff P loss and surface co-application of P-sources and WTR is a practical way of land applying the residuals. In a rainfall simulation study, we evaluated the effects of surface co-applied P-sources and an Al-WTR on runoff and leacheate bioavailable P (BAP) losses from a Florida sand. Four P-sources, namely poultry manure, Boca Raton biosolids (high water-soluble P), Pompano biosolids (moderate water-soluble P), and triple super phosphate (TSP) were surface applied at 56 and 224kgPha(-1) (by weight) to represent low and high soil P loads typical of P- and N-based amendments rates. The treatments further received surface applied WTR at 0 or 10gWTRkg(-1) soil. BAP loss masses were greater in leachate (16.4-536mg) than in runoff (0.91-46mg), but were reduced in runoff and leachate by surface applied WTR. Masses of total BAP lost in the presence of surface applied WTR were less than approximately 75% of BAP losses in the absence of WTR. Total BAP losses from each of the organic sources applied at N-based rates were not greater than P loss from TSP applied at a P-based rate. The BAP loss at the N-based rate of moderate water-soluble P-source (Pompano biosolids) was not greater than BAP losses at the P-based rates of other organic sources tested. The hazards of excess P from applying organic P-sources at N-based rates are not greater than observed at P-based rates of mineral fertilizer. Results suggest that management of the environmental P hazards associated with N-based rates of organic materials in Florida sands is possible by either applying P-sources with WTR or using a moderate water-soluble P-source. 相似文献
9.
Sources and Transport of Phosphorus to Rivers in California and Adjacent States,U.S., as Determined by SPARROW Modeling
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Joseph Domagalski Dina Saleh 《Journal of the American Water Resources Association》2015,51(6):1463-1486
The SPARROW (SPAtially Referenced Regression on Watershed attributes) model was used to simulate annual phosphorus loads and concentrations in unmonitored stream reaches in California, U.S., and portions of Nevada and Oregon. The model was calibrated using de‐trended streamflow and phosphorus concentration data at 80 locations. The model explained 91% of the variability in loads and 51% of the variability in yields for a base year of 2002. Point sources, geological background, and cultivated land were significant sources. Variables used to explain delivery of phosphorus from land to water were precipitation and soil clay content. Aquatic loss of phosphorus was significant in streams of all sizes, with the greatest decay predicted in small‐ and intermediate‐sized streams. Geological sources, including volcanic rocks and shales, were the principal control on concentrations and loads in many regions. Some localized formations such as the Monterey shale of southern California are important sources of phosphorus and may contribute to elevated stream concentrations. Many of the larger point source facilities were located in downstream areas, near the ocean, and do not affect inland streams except for a few locations. Large areas of cultivated land result in phosphorus load increases, but do not necessarily increase the loads above those of geological background in some cases because of local hydrology, which limits the potential of phosphorus transport from land to streams. 相似文献
10.
Darryl Macer 《Journal of Agricultural and Environmental Ethics》1997,10(3):249-267
The interactions between humans, animals and the environment have shaped human values and ethics, not only the genes that
we are made of. The animal rights movement challenges human beings to reconsider interactions between humans and other animals,
and maybe connected to the environmental movement that begs us to recognize the fact that there are symbiotic relationships
between humans and all other organisms. The first part of this paper looks at types of bioethics, the implications of autonomy
and the value of being alive. Then the level of consciousness of these relationships are explored in survey results from Asia
and the Pacific, especially in the 1993 International Bioethics Survey conducted in Australia, Hong Kong, India, Israel, Japan,
New Zealand, The Philippines, Russia, Singapore and Thailand. Very few mentioned animal consciousness in the survey, but there
were more biocentric comments in Australia and Japan; and more comments with the idea of harmony including humans in Thailand.
Comparisons between questions and surveys will also be made, in an attempt to describe what people imagine animal consciousness
to be, and whether this relates to human ethics of the relationships.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
This study demonstrates the integration of rehabilitation and flood management planning in a steep, boulder-bedded stream
in a coastal urban catchment on the South Island of New Zealand. The Water of Leith, the primary stream flowing through the
city of Dunedin, is used as a case study. The catchment is steep, with a short time of concentration and rapid hydrologic
response, and the lower stream reaches are highly channelized with floodplain encroachment, a high potential for debris flows,
significant flood risks, and severely degraded aquatic habitat. Because the objectives for rehabilitation and flood management
in urban catchments are often conflicting, a number of types of analyses at both the catchment and the reach scales and careful
planning with stakeholder consultation were needed for successful rehabilitation efforts. This included modeling and analysis
of catchment hydrology, fluvial geomorphologic assessment, analysis of water quality and aquatic ecology, hydraulic modeling
and flood risk evaluation, detailed feasibility studies, and preliminary design to optimize multiple rehabilitation and flood
management objectives. The study showed that all of these analyses were needed for integrated rehabilitation and flood management
and that some incremental improvements in stream ecological health, aesthetics, and public recreational opportunities could
be achieved in this challenging environment. These methods should be considered in a range of types of stream rehabilitation
projects. 相似文献
12.
David Seckler R. K. Sampath S. K. Raheja 《Journal of the American Water Resources Association》1988,24(4):855-860
ABSTRACT: This paper presents a statistically valid index for measuring the performance of irrigation systems. The index is applied to a sample of 39 farms on a watercourse under the warabandi system of irrigation management in India. It is found that while the farmers in fact irrigated almost exactly the total amount of irrigated area as designed, inter-farm variations were considerable. The index shows that the degree of error of managerial effectiveness of irrigation on this watercourse is 20 percent. Therefore it is concluded that the system is performing at 80 percent effectiveness. 相似文献
13.
Infiltration models are based on physical characteristics of the soil and initial soil moisture. For a given soil it is based on the initial soil moisture distribution. A computer simulation model for flood runoff systems (FH-Model) was used to analyze 39 sets of rainfall-runoff data on four small watersheds ranging in size from 17 to 342 square kilometers located in the Yamaska River basin in Quebec. From these analyses, parameters and coefficients have been determined for a water loss (infiltration) equation. A method for determining the loss parameters, using a nonlinear least square curve fitting technique, is presented. Expressions were made to relate the loss parameters to antecedent precipitation. The equations were tested on 11 storm rainfall and runoff events on a watershed located in the same region and close agreements were found. 相似文献
14.
Data are presented on the vegetation dynamics of two impounded marshes along the Indian River Lagoon, in east-central Florida,
USA. Vegetation in one of the marshes (IRC 12) was totally eliminated by overflooding and by hypersaline conditions (salinities
over 100 ppt) that developed there in 1979 after the culvert connecting the marsh with the lagoon was closed. Over 20% recovery
of the herbaceous halophytesSalicornia virginica, S. bigelovii, andBatis maritima was observed at that site after the culvert was reopened in 1982, but total cover in the marsh remains well below the original
75%. No recovery of mangroves was observed at this site. The second site (SLC 24), while remaining isolated from the lagoon
during much of the study, did not suffer the complete elimination of vegetation experienced at the first site. At this location,
mangroves increased in cover and frequency with a concomitant decrease in herbaceous halophytes.
Considerable damage to the vegetation was evident at IRC 12 when the impoundment was closed and flooded for mosquito control
in 1986. Although the damage was temporary, its occurrence emphasizes the need of planning and constant monitoring and adjustment
of management details as conditions within particular marshes change. Storms and hurricanes may be important in promoting
a replacement of black mangroves by red mangroves in closed impoundments because the former cannot tolerate pneumatophore
submergence for long periods of time.
University of Florida-IFAS Journal Series R-00521. 相似文献
15.
In the final analysis, sustainable agriculture must derive from applied ecology, especially the principle of the regulation of the abundance and distribution of species (and, secondarily, their activities) in space and time. Interspecific competition in natural ecosystems has its counterparts in agriculture, designed to divert greater amounts of energy, nutrients, and water into crops. Whereas natural ecosystems select for a diversity of species in communities, recent agriculture has minimized diversity in favour of vulnerable monocultures. Such systems show intrinsically less stability and resilience to perturbations. Some kinds of crop rotation resemble ecological succession in that one crop prepares the land for successive crop production. Such rotations enhance soil organic processes such as decomposition and material cycling, build a nutrient capital to sustain later crop growth, and reduce the intensity of pest buildup. Species in natural communities occur at discrete points along the r-K continuum of reproductive maturity. Clearing forested land for agriculture, rotational burning practices, and replacing perennial grassland communities by cereal monocultures moves the agricultural community towards the r extreme. Plant breeders select for varieties which yield at an earlier age and lower plant biomass, effectively moving a variety towards the r type. Features of more natural landscapes, such as hedgerows, may act as physical and biological adjuncts to agricultural production. They should exist as networks in agricultural lands to be most effective. Soil is of major importance in agroecosystems, and maintaining, deliberately, its vitality and resilience to agricultural perturbations is the very basis of sustainable land use. 相似文献
16.
Ecotechnological methods have been employed by developed countries like the United States of America, Europe, Australia and
Japan in the restoration of their degraded freshwater ecosystems. These methods according to literature sources, in many cases
have produced the desired results in these countries where they have been implemented. This article is aimed at providing
an overview on aspects of available ecotechnological methods employed in the reduction of eutrophication and acidification
and in Lake Ecosystem restoration in general. Ecotechnological methods offer great opportunities for developing countries
with tropical or subtropical climates due to their cost-effectiveness. The efficacy and potential limitations of the various
methods in their respective restorative approach is also reported in this article. 相似文献
17.
Kathryn Paxton George 《Journal of Agricultural and Environmental Ethics》1988,1(3):175-192
The maintenance of biodiversity is urged from many quarters and on grounds ranging from aesthetic considerations to its usefulness, particularly for biotechnology. But regardless of the grounds for preserving biodiversity, writers are generally in agreement that it should be preserved. But, in examining the various references biodiversity, such as species diversity, genetic diversity, and habitat diversity, it is apparent that we cannot aim to preserve biodiversityas such, since there are a number of conflicts in any such undertaking. In preserving one aspect of biodiversity, we damage another aspect. Five arguments which attempt to ground our moral concern for biodiversity are reviewed and critiqued, not only for their consistency but also for their power to move us to action. The final section of the paper shows how conflicts in the values of personal and environmental health can impair ethical action and especially policy formation.An earlier version of this paper was read at the conference on Agriculture, Food, and Human Values: Tradition and Change, Orlando, Florida, October 7–9, 1987. 相似文献
18.
Land uses such as forestry and agriculture are presumed to degrade the biodiversity of riparian wetlands in the northern temperate regions of the United States. In order to improve land use decision making in this landscape, floral and faunal communities of 15 riparian wetlands associated with low-order streams were related to their surrounding land cover to establish which organismal groups are affected by anthropogenic disturbance and whether these impacts are scale-specific. Study sites were chosen to represent a gradient of disturbance. Vascular plants of wet meadow and shrub carr communities, aquatic macro-invertebrates, amphibians, fish and birds were surveyed, and total abundance, species richness and Shannon diversity were calculated. For each site, anthropogenic disturbances were evaluated at local and landscape scales (500, 1000, 2500 and 5000 m from the site and the site catchment) from field surveys and a geographic information system (GIS). Land use data were grouped into six general land use types: urban, cultivated, rangeland, forest, wetland and water. Shrub carr vegetation, bird and fish diversity and richness generally decrease with increasing cultivation in the landscape. Amphibian abundance decreases and fish abundance increases as the proportions of open water and rangeland increases; bird diversity and richness increase with forest and wetland extent in the landscape. Wet meadow vegetation, aquatic macro-invertebrates, amphibians and fish respond to local disturbances or environmental conditions. Shrub carr vegetation, amphibians and birds are influenced by land use at relatively small landscape scales (500 and 1000 m), and fish respond to land use at larger landscape scales (2500, 5000 m and the catchment). Effective conservation planning for these riparian wetlands requires assessment of multiple organismal groups, different types of disturbance and several spatial scales.1998 Academic Press 相似文献
19.
Daniel C. Wigley Kristin Shrader-Frechette 《Journal of Agricultural and Environmental Ethics》1996,9(1):61-82
The paper begins with a brief analysis of the concepts of environmental justice and environmental racism and classism. The authors argue that pollution- and environment-related decision-making is prima facie wrong whenever it results in inequitable treatment of individuals on the basis of race or socio-economic status. The essay next surveys the history of the doctrine of free informed consent and argues that the consent of those affected is necessary for ensuring the fairness of decision-making for siting hazardous facilities. The paper also points out that equal opportunity to environmental protection and free informed consent are important rights. Finally, it presents a case study on the proposed uranium enrichment facility near Homer, Louisiana and argues that siting the plant would violate norms of distributive equity and free informed consent. It concludes that siting the facility is a case of environmental injustice and likely an example of environmental racism or classism. 相似文献
20.
Aysu Akalin Kemal Yildirim Christopher Wilson Onder Kilicoglu 《Journal of environmental psychology》2009
In this study, five different sets of single-family house façades from private suburban cooperative housing developments in Ankara, Turkey, were analyzed; with each set comprising one example each of minimum, intermediate and maximum complexity. Although the houses in each set had the same appearance when they were first built, their façades have since been altered by their owners. The main hypothesis of the study was that preference rates would be high for intermediately altered houses by showing the existence of a U-shaped relationship. On the other hand, it was hypothesized that perceived complexity and perceived impressiveness would have a linear relationship, with perceived complexity increasing and perceived impressiveness decreasing as the complexity level changed. In terms of these two basic hypotheses, it was also assumed that there would be a difference in the ratings of particular respondent groups with different backgrounds. Thus, a questionnaire was given to 100 undergraduate students of the Architecture and Engineering Departments of Gazi University, Ankara (41 from architecture and 59 from engineering). These students were asked to rate a total of 15 photographs from five housing sites with the help of five-point semantic differential scales under three headings; namely: Preference: beautiful – ugly, warm – cold, pleasant – unpleasant; Complexity: unimposing – imposing, simple – complex; and Impressiveness: impressive – unimpressive. The results proved the existence of a U-shaped relationship between complexity and preference criteria. That is, façades representing an intermediate level of complexity were favored over less and more complex ones. The façades that seemed the most impressive were the most complex ones, but these, however, were not the most preferred. Amongst these results, it was also noted that the architecture students replied in a more critical way than the engineering students as they criticized what they saw as negative design decisions. 相似文献